Influence of the Mechanical Properties of Lime Mortar on the Strength of Brick Masonry
This paper aims at improving the quality of lime mortar masonry by understanding the mechanics of mortars and masonry and their interaction. It investigates how the mortar’s compressive and flexural strengths impact the compressive and bond strength of clay brick masonry bound with calcium lime (CL) and natural hydraulic lime (NHL) mortars. It concludes that the strength of the bond has a greater impact on the compressive strength of masonry than the mortar’s strength. The masonry compressive strength increased proportionally to the strength of the bond up to 6 months. A regression analysis, giving a second order equation with coefficient of determination (R2) of 0.918, demonstrates a strong and predictable relationship between bond strength and masonry compressive strength. It was noted that CL90s mortar masonry reaching a high bond value was stronger than that built with a stronger mortar but displaying a poorer bond. Finally, the mechanics of lime mortars and their masonry are similar. The predominantly elastic behaviour of the mortars of higher hydraulic strength compares well with the elastic and brittle behaviour of their masonry, with either little (NHL2) or non-existent plasticity (NHL3.5 and 5); in contrast, the CL90 mortar and masonry exhibit a plastic behaviour.
KeywordsCompressive Strength Bond Strength Flexural Strength Lime Mortar Mortar Strength
The authors thank Paul McMahon, Architectural Heritage Division, Office of Public Works, for supporting this project. All testing was carried out in the Dept. of Civil Engineering, Trinity College Dublin. The authors thank Chris O’Donovan, Dr. Kevin Ryan and Dave McAuley for their assistance with testing; and The Traditional Lime Company, St Astier/CESA Limes, Clogrenanne Lime Ltd and Kingscourt brick for donating materials.
- 6.Hedstrom, E.G., Tarhini, K.M., Thomas, R.D., et al.: Flexural bond strength of concrete masonry prisms using PC and hydrated lime mortars. Mason. Soc. J. 9(2), 8–23 (1991)Google Scholar
- 7.Portland Cement Association (PCA): Bond strength testing of masonry. Masonry Information, Skokie (1994)Google Scholar
- 8.Venumadhava Rao, K., Venkatarama Reddy, B.V., Jagadish, K.S.: Influence of flexural bond strength on the compressive strength of masonry. In: Proceedings of the National Conference on Civil Engineering Materials and Structures, pp. 103–108. Osmania University, Hyderabad, India (1995)Google Scholar
- 10.Groot, C.J.W.S.: Effects of water on mortar brick bond. PhD thesis, University of Delft, Delft, The Netherlands (1993)Google Scholar
- 12.CEN: Method of testing cement. Determination of strength, EN 196-1 (2005)Google Scholar
- 13.CEN: Building lime. Part 2. Test methods, EN 459-2 (2001)Google Scholar
- 15.CEN: Method of test masonry: determination of compressive strength, EN 1052-1 (1999)Google Scholar
- 16.CEN: Method of test masonry: determination of flexural strength, EN 1052-2 (1999)Google Scholar
- 17.CEN: Method of test masonry: determination of bond strength, EN 1052-5 (2005)Google Scholar